As a height adjusting device for a vehicle seat, there is known a height adjusting device for a vehicle seat, which includes two pairs of spaced apart forward and rearward linkage members bridged between side frame sections of a seat cushion frame of the vehicle seat and two pairs of spaced apart brackets of upper rail members of a track mechanism for allowing the vehicle seat to be slid forward and rearward in an interior of a vehicle, connecting shafts interconnecting the linkage members, and an operating knob attached to one of the side frame sections of the seat cushion frame, and which is adapted to cause a height of the vehicle seat to be moved vertically by handling the operating knob (Japanese Patent Application Laid-Open No. 2001-138780).
The height adjusting device further includes a pinion gear arranged within the seat cushion frame, a sector gear pivotally supported through a supporting pin to the side frame section of the seat cushion frame and meshed with the pinion gear, and a linkage rod coupled at one end thereof to a portion of the sector gear which is offset from the supporting pin of the sector gear, and coupled at the other end thereof to one of the rearward linkage members.
In the height adjusting device, the pinion gear is mounted on a rotating shaft of the operating knob that is projected inward of the seat cushion frame through the one of the side frame sections of the seat cushion frame. The sector gear is pivotally supported to the side frame section of the seat cushion frame by the supporting pin that is attached to the side frame section of the seat cushion frame.
In the conventional height adjusting device, the pinion gear and the sector gear are exposed in the seat cushion frame, so that there is a possibility that any foreign materials will be caught between the pinion gear and the sector gear. Moreover, the rotating shaft of the operating knob and the supporting pin of the sector gear are simply cantilevered by the side frame section of the seat cushion frame, so that there is a possibility that when the sector gear is rotated synchronously with rotation of the pinion gear, the sector gear will be deflected, namely, the sector gear will produce runout. As a result, stable rotation of the sector gear by the pinion gear may be prevented.